Data resource mapping for frequency-coded symbols

ABSTRACT

A device and method for communicating frequency-coded symbols that include data elements and reference symbols are disclosed. In one aspect, a carrier frequency band includes a plurality of subcarrier frequency bands. Data elements are transmitted and received on respective pairs of adjacent subcarrier frequency bands to provide diversity. Reference symbols are transmitted and received on predetermined subcarrier frequency bands. Muting is applied to selected subcarrier frequency bands based on the number and frequency configuration of the reference symbols.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority benefit under 35 U.S.C. §119(e)of U.S. Provisional Patent Application No. 61/431,982, entitled “DataResource Mapping for SFBC Based Schemes in CSI-RS Subframes,” filed Jan.12, 2011, the contents of which are incorporated herein by reference intheir entirety.

TECHNICAL FIELD

The present invention relates to a device and method for communicatingfrequency-coded data elements and reference symbols, and moreparticularly, for communicating the data elements and reference symbolswhile muting all or selected subcarrier frequency bands based on thenumber and frequency configuration of the reference symbols.

BACKGROUND

Transmit diversity schemes enable increased reliability in thetransmission of data through the use of multiple antennas at thetransmitter. In a conventional transmit diversity scheme, space timeblock coding (STBC) and/or space frequency block coding (SFBC) are oftenused. One of the simplest and most commonly used STBC codes is known asthe Alamouti transmission scheme. In the Alamouti scheme, data is sentin groups of two time slots, where the symbols [s0, −s1*] are sent inthe first time slot from a two antenna transmitter (i.e., the firstsymbol s0 is sent through the first antenna, and the second symbol −s1*is sent through second antenna), and the same symbols with a certainphase shift and scaling [s1, s0*] are sent through the respectiveantennas in the second time slot. At the end of each second slot, thereceiver can use a linear combination of the signals received duringfirst and second time slots to decode s0 and s1 with a lower errorprobability as compared with the single-input-single-output (SISO) case.

One of the requirements of the Alamouti transmission scheme is that thechannel conditions must be constant, or as close to constant aspossible, during first and second time slots. In systems such as, forexample, the Third Generation Partnership Project (3GPP) Long TermEvolution (LTE), in which several modulation symbols may be multiplexedin frequency for transmission, the Alamouti scheme can be used byexploiting the frequency domain instead of the time domain (i.e., thescheme becomes an Alamouti SFBC scheme). In the Alamouti SFBC scheme,the pairs of data symbols [s0, s1] and [−s1*, s0*] are transmitted intwo frequency subcarriers instead of in two time slots. In order tocomply with the requirement that the channel conditions be as close toconstant as possible, the frequency subcarriers are typically selectedto be adjacent to one another in frequency.

In one exemplary SFBC transmission scheme, a 10-ms frame consists of 10subframes, each having a length of 1 ms. Each subframe consists of twoslots, each having a length of 0.5 ms. Each slot is configured forcommunication of seven orthogonal frequency division multiplexed (OFDM)symbols. Each OFDM symbol is communicated on 12 consecutive subcarrierfrequencies. The 12 consecutive subcarrier frequencies are referred toas a resource block (RB). Each individual subcarrier within a singleOFDM symbol is referred to as a resource element (RE).

When using a SFBC transmission scheme in a system such as 3GPP LTE, aninability to identify two consecutive subcarrier frequencies for thetransmission of the pair of data symbols may occur. For example, in someinstances, a reference symbol or a muted reference symbol may bedesignated to be transmitted in a specific subcarrier frequency band.

A new type of reference symbol, known as channel state informationreference symbol (CSI-RS) has been introduced in 3GPP LTE Release 10. Insome cases, the presence of CSI-RS can lead to SFBC blocks beingallocated to non-contiguous subcarriers if the current specificationsare followed. Moreover, muting of CSI-RS patterns is also introduced in3GPP LTE Release 10, which also leads to situations where frequency gapsinside SFBC codes appear when following current specifications.Accordingly, there is a need to address the allocation of SFBC blocks tonon-contiguous subcarriers as described above.

SUMMARY

Particular embodiments of the present invention provide methods anddevices for communicating frequency-coded symbols that include dataelements and reference symbols. In one aspect, particular subcarrierfrequency bands are designated for communication of reference symbols ormuted reference symbols. A determination is made as to which subcarrierfrequency bands can be used to communicate data, and a determination ismade as to which subcarrier bands to mute. In some instances, allsubcarrier frequency bands may be muted.

In one particular aspect, a method for data transmission on a pluralityof subcarrier frequency bands is provided. First, a number of subcarrierfrequency bands allocated for reference symbols identified as muted isdetermined, and a determination whether to mute all of the plurality ofsubcarrier frequency bands is made by applying a predetermined rule tothe determined number. If a determination not to mute all of theplurality of subcarrier frequency bands is made, subcarrier frequencybands available for transmitting data elements are identified. Theidentification may be based on identifying one or more subcarrierfrequency bands allocated for transmitting one or more correspondingreference symbols. Then, a set of pairs of subcarrier frequency bands isdetermined from the determined available subcarrier frequency bands.Each pair includes a first subcarrier frequency band and a secondsubcarrier frequency band adjacent to the first subcarrier frequencyband, wherein each subcarrier frequency band is associated with no morethan one pair. Each of the data elements is then simultaneouslytransmitted on both of the first and second subcarrier frequency bandsin a corresponding pair within the determined set of pairs.

In some embodiments, each of the data elements may be frequency codedusing space frequency block coding (SFBC). Each of the SFBC-coded dataelements and each reference symbol may be included within an orthogonalfrequency division multiplexing (OFDM) symbol. Each reference symbol mayinclude a channel state information—reference symbol (CSI-RS). If adetermination not to mute all of the plurality of subcarrier frequencybands is made, the predetermined rule may include muting each subcarrierfrequency band not included in the determined set of pairs.

In some embodiments, if a determination not to mute all of the pluralityof subcarrier frequency bands is made, the method may further includeselecting a first unpaired subcarrier frequency band that is identifiedas being available for transmitting data elements and not included inthe determined set of pairs, and determining whether a second unpairedsubcarrier frequency band that is identified as being available fortransmitting data elements and not included in the determined set ofpairs and that has a frequency separation from the first unpairedsubcarrier frequency band no greater than double a bandwidth of a singlesubcarrier frequency band exists within the plurality of subcarrierfrequency bands. If said second unpaired subcarrier frequency band isdetermined to exist, the method may further include forming a pairincluding the first and second unpaired subcarrier frequency bands andincluding the formed pair in the determined set of pairs. If said secondunpaired subcarrier frequency band is determined not to exist, themethod may include muting the first unpaired subcarrier frequency band.These steps may be repeated until all unpaired subcarrier frequencybands that are identified as being available for transmitting dataelements are muted or included in a formed pair.

In some embodiments, if the determined number of subcarrier frequencybands allocated for a reference symbol identified as muted is greaterthan two, the predetermined rule includes muting all of the plurality ofsubcarrier frequency bands. In other embodiments, a different thresholdnumber of muted reference symbols may be used for the determination ofwhether to mute all of the plurality of subcarrier frequency bands.

In another aspect, a device is provided. The device comprises aprocessor, a transmitter coupled to the processor, and at least a firstpair of transmission antennas coupled to the transmitter. The processoris configured to determine, from within a plurality of subcarrierfrequency bands, a number of subcarrier frequency bands allocated for areference symbol identified as muted, and to determine whether to muteall of the plurality of subcarrier frequency bands by applying apredetermined rule to the determined number. If a determination not tomute all of the plurality of subcarrier frequency bands is made, theprocessor is further configured to identify subcarrier frequency bandsavailable for transmitting data elements. The identification may bebased on identifying one or more subcarrier frequency bands allocatedfor transmitting one or more reference symbols. The processor is furtherconfigured to determine a set of pairs of subcarrier frequency bandsfrom said identified available subcarrier frequency bands. Each pairincludes a first subcarrier frequency band and a second subcarrierfrequency band adjacent to the first subcarrier frequency band, whereineach subcarrier frequency band is associated with no more than one pair.The processor is further configured to cause the transmitter to use theat least first pair of transmission antennas to simultaneously transmiteach of the data elements on both of the first and second subcarrierfrequency bands in a corresponding pair within the determined set ofpairs.

In some embodiments, each of the data elements may be frequency codedusing space frequency block coding (SFBC). Each of the SFBC-coded dataelements and each reference symbol may be included within an orthogonalfrequency division multiplexing (OFDM) symbol. Each reference symbol mayinclude a channel state information—reference symbol (CSI-RS). If adetermination not to mute all of the plurality of subcarrier frequencybands is made, the predetermined rule may include muting each subcarrierfrequency band not included in the determined set of pairs.

In some embodiments, if a determination not to mute all of the pluralityof subcarrier frequency bands is made, the processor may be furtherconfigured to select a first unpaired subcarrier frequency band that isidentified as being available for transmitting data elements and notincluded in the determined set of pairs, and to determine whether asecond unpaired subcarrier frequency band that is identified as beingavailable for transmitting data elements and not included in thedetermined set of pairs and that has a frequency separation from thefirst unpaired subcarrier frequency band no greater than double abandwidth of a single subcarrier frequency band exists within thepredetermined plurality of subcarrier frequency bands. If said secondunpaired subcarrier frequency band is determined to exist, the processormay be further configured to form a pair including the first and secondunpaired subcarrier frequency bands and including the formed pair in thedetermined set of pairs. If said second unpaired subcarrier frequencyband is determined not to exist, the processor may be further configuredto mute the first unpaired subcarrier frequency band. The processor maybe further configured to repeat the above steps until all subcarrierfrequency bands that are identified as being available for transmittingdata elements are muted or included in a formed pair.

In some embodiments, if the determined number of subcarrier frequencybands allocated for a reference symbol identified as muted is greaterthan two, the predetermined rule includes muting all of the plurality ofsubcarrier frequency bands. In other embodiments, a different thresholdnumber of muted reference symbols may be used for the determination ofwhether to mute all of the plurality of subcarrier frequency bands.

In yet another aspect, a method for data reception on a plurality ofsubcarrier frequency bands is provided. The method comprises determininga number of subcarrier frequency bands allocated for a reference symbolidentified as muted; and determining whether to mute all of theplurality of subcarrier frequency bands by applying a predetermined ruleto the determined number. If a determination not to mute all of theplurality of subcarrier frequency bands is made, the method furthercomprises identifying subcarrier frequency bands available for receivingdata elements. The identification may be based on identifying one ormore subcarrier frequency bands for receiving one or more correspondingreference symbols. Next, a set of pairs of subcarrier frequency bands isdetermined from said determined available subcarrier frequency bands.Each pair includes a first subcarrier frequency band and a secondsubcarrier frequency band adjacent to the first subcarrier frequencyband, wherein each subcarrier frequency band is associated with no morethan one pair. Each of the data elements is then simultaneously receivedon both of the first and second subcarrier frequency bands in acorresponding pair within the determined set of pairs.

In some embodiments, each of the data elements may be frequency codedusing space frequency block coding (SFBC). Each of the SFBC-coded dataelements and each reference symbol may be included within an orthogonalfrequency division multiplexing (OFDM) symbol. Each reference symbol mayinclude a channel state information—reference symbol (CSI-RS). If adetermination not to mute all of the plurality of subcarrier frequencybands is made, the predetermined rule may include muting each subcarrierfrequency band not included in the determined set of pairs.

In some embodiments, if a determination not to mute all of the pluralityof subcarrier frequency bands is made, the method may further includeselecting a first unpaired subcarrier frequency band that is identifiedas being available for receiving data elements and not included in thedetermined set of pairs, and determining whether a second unpairedsubcarrier frequency band that is identified as being available forreceiving data elements and not included in the determined set of pairsand that has a frequency separation from the first unpaired subcarrierfrequency band no greater than double a bandwidth of a single subcarrierfrequency band exists within the plurality of subcarrier frequencybands. If said second unpaired subcarrier frequency band is determinedto exist, the method may further include forming a pair including thefirst and second unpaired subcarrier frequency bands and including theformed pair in the determined set of pairs. If said second unpairedsubcarrier frequency band is determined not to exist, the method mayfurther include muting the first unpaired subcarrier frequency band. Themethod may further include repeating the above steps until all unpairedsubcarrier frequency bands that are identified as being available forreceiving data elements are muted or included in a pair.

In some embodiments, if the determined number of subcarrier frequencybands allocated for a reference symbol identified as muted is greaterthan two, the predetermined rule includes muting all of the plurality ofsubcarrier frequency bands. In other embodiments, a different thresholdnumber of muted reference symbols may be used for the determination ofwhether to mute all of the plurality of subcarrier frequency bands.

In still another aspect, a device is provided. The device comprises aprocessor, a receiver coupled to the processor, and at least a firstpair of reception antennas coupled to the receiver. The processor isconfigured to determine, from within a plurality of subcarrier frequencybands, a number of subcarrier frequency bands allocated for a referencesymbol identified as muted, and to determine whether to mute all of theplurality of subcarrier frequency bands by applying a predetermined ruleto the determined number. If a determination not to mute all of theplurality of subcarrier frequency bands is made, the processor isfurther configured to identify subcarrier frequency bands available forreceiving data elements. The identification may be based on identifyingone or more subcarrier frequency bands for receiving one or morereference symbols. The processor is further configured to determine aset of pairs of subcarrier frequency bands from said identifiedavailable subcarrier frequency bands. Each pair includes a firstsubcarrier frequency band and a second subcarrier frequency bandadjacent to the first subcarrier frequency band, wherein each subcarrierfrequency band is associated with no more than one pair. The processoris further configured to cause the receiver to use the at least firstpair of reception antennas to simultaneously receive each of the dataelements on both of the first and second subcarrier frequency bands in acorresponding pair within the determined set of pairs.

In some embodiments, each of the data elements may be frequency codedusing space frequency block coding (SFBC). Each of the SFBC-coded dataelements and each reference symbol may be included within an orthogonalfrequency division multiplexing (OFDM) symbol. Each reference symbol mayinclude a channel state information—reference symbol (CSI-RS). If adetermination not to mute all of the plurality of subcarrier frequencybands is made, the predetermined rule may include muting each subcarrierfrequency band not included in the determined set of pairs.

In some embodiments, if a determination not to mute all of the pluralityof subcarrier frequency bands is made, the processor may be furtherconfigured to select a first unpaired subcarrier frequency band that isidentified as being available for receiving data elements and notincluded in the determined set of pairs, and to determine whether asecond unpaired subcarrier frequency band that is identified as beingavailable for receiving data elements and not included in the determinedset of pairs and that has a frequency separation from the first unpairedsubcarrier frequency band no greater than double a bandwidth of a singlesubcarrier frequency band exists within the predetermined plurality ofsubcarrier frequency bands. If said second unpaired subcarrier frequencyband is determined to exist, the processor may be further configured toform a pair including the first and second unpaired subcarrier frequencybands and to include the formed pair in the determined set of pairs. Ifsaid second unpaired subcarrier frequency band is determined not toexist, the processor may be further configured to mute the firstunpaired subcarrier frequency band. The processor may be furtherconfigured to repeat the above steps until all subcarrier frequencybands that are identified as being available for receiving data elementsare muted or included in a pair.

In some embodiments, if the determined number of subcarrier frequencybands allocated for a reference symbol identified as muted is greaterthan two, the predetermined rule includes muting all of the plurality ofsubcarrier frequency bands. In other embodiments, a different thresholdnumber of muted reference symbols may be used for the determination ofwhether to mute all of the plurality of subcarrier frequency bands.

The above and other aspects and embodiments are described below withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form partof the specification, illustrate various embodiments of the presentdisclosure and, together with the description, further serve to explainthe principles of the disclosure and to enable a person skilled in thepertinent art to make and use the embodiments disclosed herein. In thedrawings, like reference numbers indicate identical or functionallysimilar elements.

FIG. 1 illustrates an architecture of a wireless communication systemaccording to an exemplary embodiment of the present invention.

FIG. 2 is a block diagram of a base station as used in the system ofFIG. 1.

FIG. 3 is a block diagram of a wireless user equipment (UE)communication device as used in the system of FIG. 1.

FIG. 4 is a first exemplary allocation of subcarrier frequency bandsaccording to an exemplary embodiment of the present invention.

FIG. 5 is an exemplary depiction of allocation islands of resourceblocks according to an exemplary embodiment of the present invention.

FIG. 6A is a second exemplary allocation of subcarrier frequency bandsaccording to an exemplary embodiment of the present invention.

FIG. 6B is a third exemplary allocation of subcarrier frequency bandsaccording to an exemplary embodiment of the present invention.

FIG. 7 is a flow chart illustrating a process for transmitting dataelements and reference symbols while muting selected subcarrierfrequency bands, in accordance with exemplary embodiments of the presentinvention.

FIG. 8 is a block diagram illustrating example software components of awireless UE communication device or a base station, in accordance withexemplary embodiments of the present invention.

FIG. 9 is a flow chart illustrating a process for receiving dataelements and reference symbols while muting selected subcarrierfrequency bands, in accordance with exemplary embodiments of the presentinvention.

FIG. 10 is a block diagram illustrating example software components of awireless UE communication device or a base station, in accordance withexemplary embodiments of the present invention.

DETAILED DESCRIPTION

In exemplary embodiments of the disclosed devices and methods, anapplication of a muting rule in subframes having reference symbols andin subframes having up to a predetermined number of muted referencesymbol patterns is described. The muting rules described herein providean effective means for eliminating frequency gaps in SFBC codes.Further, the overhead increased by such muting is minimized, because themuting rule effectively minimizes the number of resource elements to bemuted. Moreover, the cases of subframes having more than a certainnumber of muted reference symbol patterns are also covered by thedescribed solutions. In these cases, all data resource elements aremuted when SFBC schemes are used.

FIG. 1 illustrates an example wireless communication system 100. Asshown, wireless communication system 100 includes a wireless network105, base stations 110, and wireless user equipment (UE) communicationdevices 115. Examples of wireless UE communication devices includemobile telephones, personal digital assistants, electronic readers,portable electronic tablets, personal computers, and laptop computers.

Referring now to FIG. 2, FIG. 2 illustrates a block diagram of a basestation 110 according to exemplary embodiments of the disclosedsolution. As shown in FIG. 2, the base station 110 may include: a dataprocessing system 220, which may include one or more microprocessorsand/or one or more circuits, such as an application specific integratedcircuit (ASIC), Field-programmable gate arrays (FPGAs), and the like;network interface 210; and a data storage system 225, which may includeone or more non-volatile storage devices and/or one or more volatilestorage devices (e.g., random access memory (RAM)). The networkinterface 210 is connected to transceiver 240, which is configured totransmit and receive signals via an antenna array 245. In embodimentswhere data processing system 220 includes a microprocessor, computerreadable program code 235 may be stored in a computer readable medium230, such as, but not limited, to magnetic media (e.g., a hard disk),optical media (e.g., a DVD), memory devices (e.g., random accessmemory), and the like. In some embodiments, computer readable programcode 235 is configured such that when executed by a processor, code 235causes the data processing system 220 to perform steps described below(e.g., steps described below with reference to the flow charts shown inFIGS. 8 and/or 10). In other embodiments, the base station 110 isconfigured to perform steps described above without the need for code235. That is, for example, data processing system 220 may consist merelyof one or more ASICs. Hence, the features of the present inventiondescribed above may be implemented in hardware and/or software. Forexample, in particular embodiments, the functional components of thebase station described above may be implemented by data processingsystem 220 executing computer instructions 235, by data processingsystem 220 operating independent of any computer instructions 235, or byany suitable combination of hardware and/or software.

Referring now to FIG. 3, FIG. 3 illustrates a block diagram of awireless UE communication device 115 according to some embodiments ofthe invention. As shown in FIG. 3, wireless UE communication device 115may include: a data processing system 310, which may include one or moremicroprocessors and/or one or more circuits, such as an applicationspecific integrated circuit (ASIC), field-programmable gate arrays(FPGAs), and the like; a transceiver 305 for transmitting data to (andreceiving data from) base station 110 via antenna array 330; and a datastorage system 315, which may include one or more non-volatile storagedevices and/or one or more volatile storage devices (e.g., random accessmemory (RAM)). In embodiments where data processing system 310 includesa microprocessor, computer readable program code 325 may be stored in acomputer readable medium 320, such as, but not limited, to magneticmedia (e.g., a hard disk), optical media (e.g., a DVD), memory devices(e.g., random access memory), and the like. In some embodiments,computer readable program code 325 is configured such that when executedby a processor, code 325 causes wireless UE communication device 115 toperform steps described below (e.g., steps described below withreference to the flow charts shown in FIGS. 8 and 10). In otherembodiments, wireless UE communication device 115 is configured toperform steps described above without the need for code 325. That is,for example, data processing system 310 may consist merely of one ormore ASICs. Hence, the features of the present invention described abovemay be implemented in hardware and/or software. For example, inparticular embodiments, the functional components of wireless UEcommunication device 115 described above may be implemented by dataprocessing system 310 executing computer instructions 325, by dataprocessing system 310 operating independent of any computer instructions325, or by any suitable combination of hardware and/or software.

In exemplary embodiments of the disclosed devices and methods, the basestation 110 and the wireless UE communication device 115 may beconfigured to communicate with each other by using an SFBC transmissionscheme with diversity to communicate orthogonal frequency divisionmultiplexed (OFDM) symbols that include data elements and referencesymbols. Referring now to FIG. 4, a first exemplary allocation ofsubcarrier frequency bands is illustrated. In the allocation of FIG. 4,there are twelve consecutive subcarrier frequency bands 421-432, and twoconsecutive time slots 401, 402. The third subcarrier 423 has beendesignated for transmission of a CSI-RS reference symbol, and all of theremaining subcarriers are available for data transmission. Thus, usingthe Alamouti SFBC scheme causes the following allocations: Data elementss1 and s2 are paired for transmission on respective subcarriers 421 and422 at time 401; data elements s3 and s4 are paired for transmission onrespective subcarriers 424 and 425 at time 401; data elements s5 and s6are paired for transmission on respective subcarriers 426 and 427 attime 401; data elements s7 and s8 are paired for transmission onrespective subcarriers 428 and 429 at time 401; data elements s9 and s10are paired for transmission on respective subcarriers 430 and 431 attime 401; data elements s11 and s12 are paired for transmission onrespective subcarriers 432 (at time 401) and 421 (at time 402); dataelements s13 and s14 are paired for transmission on respectivesubcarriers 422 and 424 at time 402; data elements s15 and s16 arepaired for transmission on respective subcarriers 425 and 426 at time402; data elements s17 and s18 are paired for transmission on respectivesubcarriers 427 and 428 at time 402; data elements s19 and s20 arepaired for transmission on respective subcarriers 429 and 430 at time402; and data elements s21 and s22 are paired for transmission onrespective subcarriers 431 and 432 at time 402. Accordingly, due to thepresence of reference symbols in subcarrier 423, one of the SFBC blocks(i.e., s11, s12) is paired for transmission of two subcarriers which areseparated in frequency from one another by a gap that is equal to 10subcarrier frequency bandwidths. This causes the channel conditions tobe significantly different for these two data elements, thereby leadingto performance degradation at the receiver.

Particular embodiments of the devices and methods disclosed herein avoidfrequency gaps inside SFBC blocks by applying muting rules for the datachannel (referred to as the physical downlink shared channel, or PDSCH,in 3GPP LTE) when SFBC is used as the transmission scheme in a subframethat is also carrying one or more reference symbols, or one or moremuted reference symbols. The muting rules can be applied in a receiveror in a transmitter. Muting rules may include muting one or more dataelements. In some instances, the muting rules may include muting alldata elements in the OFDM symbols carrying muted CSI-RS referencesymbols, depending on the number and frequency configuration of themuted CSI-RS reference symbols.

In exemplary embodiments of the disclosed devices and methods, when theSFBC transmission scheme is used in combination with reference symbols,and in order to avoid situations where SFBC blocks are split betweennon-adjacent subcarriers, the non-adjacent subcarriers are muted. In anexemplary embodiment, a muting rule may be applied such that the mutingrule identifies blocks of contiguous resource blocks which are allocatedto the same wireless user communication device, referred to herein asallocation islands, and then mutes only one non-adjacent resourceelement in each resource block in which there is a non-adjacent resourceelement. For example, the first or last resource element of the resourceblock may be muted, or a different resource element may be selected formuting, depending on the configuration of the reference symbol pattern.The muting rule can be selectively applied only at each such island andeven then, only in islands where there is a non-adjacent resourceelement. For example, in islands with an even number of resource blocks,all resource elements can be paired with an adjacent resource element.Thus, in practice, the muting rule can be designed to identify andhandle islands having an odd number of allocated resource blocks. Inaddition, subframes having up to a certain number of muted referencesymbols can be handled through the use of this type of muting rule.

Referring to FIG. 5, an exemplary depiction of allocation islands ofresource blocks is illustrated. Each of allocation islands 510, 515, and525 is an island of a single resource block; allocation island 520 hastwo resource blocks; and allocation island 505 has five resource blocks.Thus, by applying the muting rule described above, because each ofislands 505, 510, 515, and 525 has an odd number of resource blocks, asingle resource element in each of these resource blocks may be muted.However, because island 520 has an even number of resource blocks, allresource elements can be paired with an adjacent resource element, andthus, no muting is required.

The application of the muting rule may also be dependent on the numberof reference symbols configured. For example, the muting rule may beapplied where either one or two antenna ports using CSI-RS referencesymbols are used, but the muting rule may not be applied if the numberof antenna ports using CSI-RS reference symbols is four or eight.

In exemplary embodiments of the disclosed devices and methods, insubframes that include at least a predetermined number of mutedreference symbols, the muting rule may include muting all data resourceelements for SFBC schemes in the OFDM symbols where the muted referencesymbols are included. However, in some OFDM symbols that include mutedreference symbols, it may be possible to transmit data on selectedsubcarriers while muting other non-paired subcarriers. This may occurunder certain channel conditions, such as, for example, low delayspread, and when the number of muted reference symbol patterns is low.In these instances, the frequency gaps present inside the SFBC blocksmust be relatively small, i.e., not greater than one or two subcarrierbandwidths, thereby yielding approximately the same channel conditionsand not compromising the reliability of the communication. The number ofmuted CSI-RS patterns used as a threshold for this decision can be aparameter configured according to the channel conditions or could befixed to a value.

Accordingly, in an exemplary embodiment, a rule for transmitting orreceiving data on a plurality of subcarrier frequencies may include thefollowing: First, determine the subcarrier frequencies that areallocated for reference symbols and for muted reference symbols. Next,from the remaining subcarriers, form pairs of mutually adjacentsubcarriers, and then determine a set of unpaired subcarriers. Next,determine whether each unpaired subcarrier can be paired with anotherunpaired subcarrier such that a sufficiently small frequency gap betweenthe two subcarriers is present. In one embodiment, the frequency gap canbe no greater than one subcarrier bandwidth. However, this determinationcan be made based on the actual channel conditions. Finally, mute eachremaining unpaired subcarrier. In some instances, this may result inmuting all subcarriers.

Referring now to FIG. 6A, a second exemplary allocation of subcarrierfrequency bands is illustrated. In this allocation, subcarriers 621 and627 are designated for transmission of CSI-RS reference symbols, andsubcarriers 623, 624, 625, 629, 630, and 631 are designated for mutedCSI-RS reference symbols. Thus, it is not possible to form any pairs ofmutually adjacent subcarriers for data transmission. Using the AlamoutiSFBC scheme would cause the following allocations: Data elements s1 ands2 are transmitted on subcarriers 622 and 626 at time 601; data elementss3 and s4 are transmitted on subcarriers 628 and 632 at time 601; dataelements s5 and s6 are transmitted on subcarriers 622 and 626 at time602; and data elements s7 and s8 are transmitted on subcarriers 628 and632 at time 602. However, in all four of these pairings of dataelements, the frequency gap between the two respective subcarriers isequal to three times the subcarrier bandwidth, which causes anunacceptable performance degradation at the receiver. Thus, in thisinstance, all subcarriers are muted.

Referring now to FIG. 6B, a third exemplary allocation of subcarrierfrequency bands is illustrated. In this allocation, subcarriers 651 and657 are allocated for transmission of CSI-RS reference symbols, andsubcarriers 653 and 659 are allocated for muted CSI-RS referencesymbols. Pairs of mutually adjacent subcarriers may include thefollowing: Data elements s3 and s4 are transmitted on subcarriers 655and 656 at time 641; data elements s7 and s8 are transmitted onsubcarriers 661 and 662 at time 641; data elements s11 and s12 aretransmitted on subcarriers 655 and 656 at time 642; and data elementss15 and s16 are transmitted on subcarriers 661 and 662 at time 642.Then, from the unpaired subcarriers, new pairs may be formed as follows:Data elements s1 and s2 may be transmitted on subcarriers 652 and 654 attime 641, because the frequency gap between subcarriers 652 and 654 isequal to only one subcarrier bandwidth, which is deemed to be asufficiently small frequency gap to yield approximately constant channelconditions. Similarly, data elements s5 and s6 may be transmitted onsubcarriers 658 and 660 at time 641; data elements s9 and s10 may betransmitted on subcarriers 652 and 654 at time 642; and data elementss13 and s14 may be transmitted on subcarriers 658 and 660 at time 642,all based on the respective frequencies gaps being equal to onesubcarrier bandwidth. Thus, in this instance, it is not necessary tomute the entire OFDM symbol, despite the allocation of some subcarriersto muted reference symbols.

Referring now to FIG. 7, a flow chart 700 illustrating a process forOFDM data transmission on a plurality of subcarrier frequency bands, inaccordance with exemplary embodiments of the disclosed devices andmethods, is shown. In the first step 705 of the process, a number ofsubcarrier frequency bands allocated for muted reference symbols, suchas, for example, CSI-RS reference symbols, is determined. Then, at step710, the determined number is used to determine whether to mute all ofthe subcarrier frequency bands. If a determination is made to mute allsubcarrier frequency bands, then the entire OFDM symbol is muted at step715.

If a determination not to mute all subcarrier frequency bands is made,then at step 720, subcarrier frequency bands that are available fortransmitting data elements are identified. This identification may bemade based on subcarrier frequency bands that are allocated forreference symbols, such as CSI-RS reference symbols. Then, at step 725,a set of pairs of mutually adjacent subcarrier frequency bands isdetermined.

At step 730, each data element is transmitted on both subcarrierfrequency bands within a pair from the set of pairs. Finally, at step735, the predetermined rule is applied to the unpaired subcarrierfrequency bands to determine whether to form new pairs and/or muteindividual subcarrier frequency bands.

The process illustrated in flow chart 700 may further include, at step740, selecting a first unpaired subcarrier frequency band that isidentified as being available for transmitting data elements and notincluded in the determined set of pairs, and at step 745, determiningwhether a second unpaired subcarrier frequency band that is identifiedas being available for transmitting data elements and not included inthe determined set of pairs and that has a frequency separation from thefirst unpaired subcarrier frequency band no greater than double abandwidth of a single subcarrier frequency band exists within theplurality of subcarrier frequency bands. If the second unpairedsubcarrier frequency band is determined to exist, then at step 750, apair including the first and second unpaired subcarrier frequency bandsand including the formed pair in the determined set of pairs is formed.If the second unpaired subcarrier frequency band is determined not toexist, that at step 755, the first unpaired subcarrier frequency band ismuted. These steps may be repeated until all unpaired subcarrierfrequency bands that are identified as being available for transmittingdata elements are muted or included in a formed pair.

In exemplary embodiments, if the determined number of subcarrierfrequency bands allocated for a reference symbol identified as muted isgreater than two, the predetermined rule includes muting all of theplurality of subcarrier frequency bands. Alternatively, a differentthreshold number of muted reference symbols may be used for thedetermination of whether to mute all of the plurality of subcarrierfrequency bands.

Referring now to FIG. 8, a block diagram 800 illustrating examplesoftware components of a wireless UE communication device 115 or a basestation 110, in accordance with exemplary embodiments of the discloseddevices and methods, is shown. First, at 805, a set of instructions fordetermining a number of subcarrier frequency bands allocated for mutedreference symbols, such as, for example, CSI-RS reference symbols, isexecuted. Then, at 810, a set of instructions for using the determinednumber to determine whether to transmit data or to mute an entire OFDMsymbol is executed.

At 815, a set of instructions for identifying subcarrier frequency bandsavailable for transmitting data elements is executed. Then, at 820, aset of instructions for determining a set of pairs of mutually adjacentsubcarrier frequency bands is executed.

At 825, a set of instructions for transmitting each data element on bothsubcarrier frequency bands within a pair is executed. Finally, at 830, aset of instructions for applying the predetermined rule to the unpairedsubcarrier frequency bands is executed. The application of the ruledetermines whether to form new pairs and/or mute individual subcarrierfrequency bands.

The example software components of a wireless UE communication device115 or a base station 110 in block diagram 800 may further include, at835, a set of instructions for selecting a first unpaired subcarrierfrequency band that is identified as being available for transmittingdata elements and not included in the determined set of pairs, and at840, a set of instructions for determining whether a second unpairedsubcarrier frequency band that is identified as being available fortransmitting data elements and not included in the determined set ofpairs and that has a frequency separation from the first unpairedsubcarrier frequency band no greater than double a bandwidth of a singlesubcarrier frequency band exists within the predetermined plurality ofsubcarrier frequency bands. If the second unpaired subcarrier frequencyband is determined to exist, then at 845, a set of instructions forforming a pair including the first and second unpaired subcarrierfrequency bands and including the formed pair in the determined set ofpairs is included. If the second unpaired subcarrier frequency band isdetermined not to exist, then at 850, a set of instructions for mutingthe first unpaired subcarrier frequency band is included. The aboveinstructions may be repeated until all subcarrier frequency bands thatare identified as being available for transmitting data elements aremuted or included in a formed pair.

In exemplary embodiments, if the determined number of subcarrierfrequency bands allocated for a reference symbol identified as muted isgreater than two, the predetermined rule includes muting all of theplurality of subcarrier frequency bands. Alternatively, a differentthreshold number of muted reference symbols may be used for thedetermination of whether to mute all of the plurality of subcarrierfrequency bands.

Referring now to FIG. 9, a flow chart 900 illustrating a process forOFDM data reception on a plurality of subcarrier frequency bands, inaccordance with exemplary embodiments of the disclosed devices andmethods, is shown. In the first step 905 of the process, a number ofsubcarrier frequency bands allocated for muted reference symbols, suchas, for example, CSI-RS reference symbols, is determined. Then, at step910, the determined number is used to determine whether to mute all ofthe subcarrier frequency bands. If a determination is made to mute allsubcarrier frequency bands, then the entire OFDM symbol is muted at step915.

If a determination not to mute all subcarrier frequency bands is made,then at step 920, subcarrier frequency bands that are available forreceiving data elements are identified. This identification may be madebased on subcarrier frequency bands that are allocated for referencesymbols, such as CSI-RS reference symbols. Then, at step 925, a set ofpairs of mutually adjacent subcarrier frequency bands is determined.

At step 930, each data element is received on both subcarrier frequencybands within a pair. At step 935, the predetermined rule is applied tothe unpaired subcarrier frequency bands to determine whether to form newpairs and/or mute individual subcarrier frequency bands.

The process illustrated in flow chart 900 may further include, at step940, selecting a first unpaired subcarrier frequency band that isidentified as being available for receiving data elements and notincluded in the determined set of pairs, and at step 945, determiningwhether a second unpaired subcarrier frequency band that is identifiedas being available for receiving data elements and not included in thedetermined set of pairs and that has a frequency separation from thefirst unpaired subcarrier frequency band no greater than double abandwidth of a single subcarrier frequency band exists within theplurality of subcarrier frequency bands. If the second unpairedsubcarrier frequency band is determined to exist, then at step 950, apair including the first and second unpaired subcarrier frequency bandsand including the formed pair in the determined set of pairs is formed.If the second unpaired subcarrier frequency band is determined not toexist, then at step 955, the first unpaired subcarrier frequency band ismuted. These steps may be repeated until all unpaired subcarrierfrequency bands that are identified as being available for receivingdata elements are muted or included in a pair.

In exemplary embodiments, if the determined number of subcarrierfrequency bands allocated for a reference symbol identified as muted isgreater than two, the predetermined rule includes muting all of theplurality of subcarrier frequency bands. Alternatively, a differentthreshold number of muted reference symbols may be used for thedetermination of whether to mute all of the plurality of subcarrierfrequency bands.

Referring now to FIG. 10, a block diagram 1000 illustrating examplesoftware components of a wireless UE communication device 115 or basestation 110, in accordance with exemplary embodiments of the discloseddevices and methods, is shown. First, at 1005, a set of instructions fordetermining a number of subcarrier frequency bands allocated for mutedreference symbols, such as, for example, CSI-RS reference symbols, isexecuted. Then, at 1010, a set of instructions for using the determinednumber to determine whether to accept reception of data or mute anentire OFDM symbol is executed.

At 1015, a set of instructions for identifying subcarrier frequencybands available for receiving data elements is executed. Then, at 1020,a set of instructions for determining a set of pairs of mutuallyadjacent subcarrier frequency bands is executed.

At 1025, a set of instructions for receiving each data element on bothsubcarrier frequency bands within a pair is executed. Finally, at 1030,a set of instructions for applying the predetermined rule to theunpaired subcarrier frequency bands is executed. The application of therule determines whether to form new pairs and/or to mute individualsubcarrier frequency bands.

The example software components of a wireless UE device or a basestation in block diagram 1000 may further include, at 1035, a set ofinstructions for selecting a first unpaired subcarrier frequency bandthat is identified as being available for receiving data elements andnot included in the determined set of pairs, and at 1040, a set ofinstructions for determining whether a second unpaired subcarrierfrequency band that is identified as being available for receiving dataelements and not included in the determined set of pairs and that has afrequency separation from the first unpaired subcarrier frequency bandno greater than double a bandwidth of a single subcarrier frequency bandexists within the predetermined plurality of subcarrier frequency bands.If the second unpaired subcarrier frequency band is determined to exist,then at 1045, a set of instructions for forming a pair including thefirst and second unpaired subcarrier frequency bands and to include theformed pair in the determined set of pairs is included. If the secondunpaired subcarrier frequency band is determined not to exist, that at1050, a set of instructions for muting the first unpaired subcarrierfrequency band is included. The above instructions may be repeated untilall subcarrier frequency bands that are identified as being availablefor receiving data elements are muted or included in a pair.

In exemplary embodiments, if the determined number of subcarrierfrequency bands allocated for a reference symbol identified as muted isgreater than two, the predetermined rule includes muting all of theplurality of subcarrier frequency bands. Alternatively, a differentthreshold number of muted reference symbols may be used for thedetermination of whether to mute all of the plurality of subcarrierfrequency bands.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. For example, exemplary embodiments of the disclosed solutionmay be applicable to any of the following: Third Generation PartnershipProject Long Term Evolution (3GPP LTE) systems; Wideband Code DivisionMultiple Access (WCDMA) systems; Worldwide Interoperability forMicrowave Access (WiMAX) systems; Ultra Mobile Broadband (UMB) systems;and any other communications systems that use diversity forcommunication of data elements and reference symbols. Thus, the breadthand scope of the present disclosure should not be limited by any of theabove-described exemplary embodiments. Moreover, any combination of theabove-described elements in all possible variations thereof isencompassed by the disclosure unless otherwise indicated herein orotherwise clearly contradicted by context.

Additionally, while the processes described above and illustrated in thedrawings are shown as a sequence of steps, this was done solely for thesake of illustration. Accordingly, it is contemplated that some stepsmay be added, some steps may be omitted, the order of the steps may bere-arranged, and some steps may be performed in parallel.

1-28. (canceled)
 29. A device comprising: a processor; a transmittercoupled to the processor; and at least one pair of antennas coupled tothe transmitter, wherein the processor is configured to: identify one ormore subcarrier frequency bands for transmitting one or morecorresponding reference symbols; determine a number of availablesubcarrier frequency bands for transmitting data symbols; determinewhether to transmit the data symbols on the available subcarrierfrequency bands based at least in part on a predetermined rule, whereinthe predetermined rule includes muting all of the plurality ofsubcarrier bands of the carrier frequency when the determined number ofavailable subcarrier frequency bands is an odd number; and mute, inresponse to the determining whether to transmit, all of the plurality ofsubcarrier bands of the carrier frequency.
 30. The device according toclaim 29, wherein the predetermined rule further includes allowingtransmission of data symbols on the available subcarrier frequency bandswhen the determined number of the available subcarrier frequency bandsis an even number.
 31. The device according to claim 29, wherein each ofthe data symbols is frequency coded using space frequency block coding(SFBC).
 32. The device according to claim 31, wherein each of theSFBC-coded data symbols is included in an orthogonal frequency divisionmultiplexing (OFDM) symbol.
 33. The device according to claim 29,wherein the one or more reference signals are identified as muted. 34.The device according to claim 33, wherein the one or more referencesignals identified as muted include a channel state informationreference symbol (CSI-RS).
 35. The device according to claim 29, whereinthe predetermined rule further includes muting all of the plurality ofsubcarrier bands of the carrier frequency when a number of theidentified one or more subcarrier frequency bands for transmitting oneor more corresponding reference symbols is greater than a thresholdnumber.
 36. A method for transmitting data on a carrier frequency bandhaving a plurality of subcarrier frequency bands, comprising:identifying one or more subcarrier frequency bands for transmitting oneor more corresponding reference symbols; determining a number ofavailable subcarrier frequency bands for transmitting data symbols;determining whether to transmit the data symbols on the availablesubcarrier frequency bands based at least in part on a predeterminedrule, wherein the predetermined rule includes muting all of theplurality of subcarrier bands of the carrier frequency when thedetermined number of available subcarrier frequency bands is an oddnumber; and muting, in response to the determining, all of the pluralityof subcarrier bands of the carrier frequency, wherein the predeterminedrule further includes allowing transmission of data symbols on theavailable subcarrier frequency bands when the determined number of theavailable subcarrier frequency bands is an even number.
 37. The methodaccording to claim 36, wherein each of the data symbols is frequencycoded using space frequency block coding (SFBC).
 38. The methodaccording to claim 37, wherein each of the SFBC-coded data symbols isincluded in an orthogonal frequency division multiplexing (OFDM) symbol.39. The method according to claim 36, wherein the one or more referencesignals are identified as muted.
 40. The method according to claim 39,wherein the one or more reference signals identified as muted include achannel state information reference symbol (CSI-RS).
 41. The methodaccording to claim 36, wherein the predetermined rule further includesmuting all of the plurality of subcarrier bands of the carrier frequencywhen a number of the identified one or more subcarrier frequency bandsfor transmitting one or more corresponding reference symbols is greaterthan a threshold number.